I used a paint removing heat gun to heat the perspex up just until the protective backing starts to bubble. A really hot hair dryer might work, but i've not tried that. Heat both sides, then when it's plyable, bend it, using a wooden brace/mould and another wooden block to hold it in place.  I have seen some attempts at using a toaster to heat the perspex, but you have to be very careful as they can radiate too much heat for small bends.

Hello from France.

I was thinking ( yes I do it now and again ) of how I could fix my Pentax to the bike, and now I have the aswer. Super 100%.

Tell me how do you bend the perspex as all I do it break it?

Keep the grey coming long and slow